The Clinical Core of the Arizona ADCC is a consortium of six recruitment sites (Banner Alzheimer Institute, Barrow Neurological Institute, Mayo Clinic Arizona, Banner Sun Health Research Institute, and the University of Arizona Health Sciences Center and VA medical Center) providing catchment areas throughout the state that function as a standardized unit under a single Clinical Core Director. The Clinical Core maintains a target of 500 participants at all stages of the aging-dementia spectrum including 325 normal controls, 75 patients with mild cognitive impairment (MCI), and 100 with Alzheimer's disease (AD) and other forms of degenerative dementia. Embedded within these diagnostic categories are defined Latino and Native American cohorts. The Clinical Core capitalizes on our multi-institutional diagnostic consensus conference, centralized data management program, and close working relationships with each of the other Cores. All subjects undergo standardized diagnostic testing that: 1) fulfills strict entrance criteria;2) includes demographic, historical, medical, neurological, psychiatric, neuropsychological, and genetic measures;3) incorporates the NACC Uniform Data Set (UDS);and 4) employs culturally sensitive test procedures. Patients eligible for enrollment and those completing annual follow-up are discussed in a biweekly diagnostic consensus conference. All undergo apolipoprotein E (APOE) genotyping at entry, and an annual standardized neuropsychological battery of tests at all sites. Patient eligibility for and participation in ongoing research projects is tracked and reviewed on an ongoing basis. All are offered enrollment in the Brain Donation Program for neuropathological confirmation of clinical diagnoses, though brain donation is not required of members of culturally sensitive diversity subgroups (Latino and Native Americans). Ancillary programs of longitudinally studied aging normal controls also receive the NACC UDS supported through other funding mechanisms. These cohorts provide unique opportunities to study the transition between cognitive normality and MCI in persons at differential risk for AD and to capitalize on our strengths in maging, genomics, cognitive neuroscience, and other research methods. To address the goals of the ADCC, subjects and data from independently funded projects are now available as a resource to other researchers, being used in other studies, and will be followed prospectively using the UDS.